1. Field of the Invention
This invention relates to the construction of sleeves for use with paperboard cups. Such structures of this type, generally, employ a paperboard sleeve backed with hot-melt glue dots which are used to improve the insulating characteristics of a paperboard cup to the same level of common polystyrene cups.
2. Description of the Related Art
Common single-use coffee cups are primarily made of paperboard or polystyrene. It is well known that the thermal insulation characteristics of polystyrene cups are far superior to those of either kraft or bleached paperboard cups. When hot coffee is poured into a single-use cup, the cup surface temperature rises to a maximum in a few seconds, then slowly cools with the coffee back to ambient temperature. If the maximum cup surface temperature exceeds about 140.degree. F., it is painful for an individual to hold the cup. The surface of a common polystyrene cup, nominally 0.090 in. thick, does not reach this threshold, but that of any single paperboard cup almost always exceeds it.
It is well known to employ various sleeve designs for cups which emphasize insulation capabilities. Exemplary of such sleeves are U.S. Pat. No. 5,205,473 ('473) to D. W. Coffin, Sr., entitled "Recyclable Corrugated Beverage Container and Holder," U.S. Pat. No. 5,425,497 ('497) to J. Sorensen, entitled "Cup Holder," U.S. Pat. No. 5,667,135 ('135) to R. J. Schaefer, entitled "Thermal Insulating Sleeve for Drink Cups," U.S. Pat. No. 5,746,372 ('372) to 0. Spence, entitled "Biodegradable Cup Holder," U.S. Pat. No. 5,794,843 ('843) to R. S. Sanchez, entitled "Cup Wrap," U.S. Pat. No. 5,826,786 ('786) to J. Dickert, entitled "Cup Holder Sleeve in Pre-Assembled Flat-Folded Form," and U.S. Pat. No. 5,842,633 ('633) to R. I. Nurse, entitled "Sleeve for Beverage Cups." While these references disclose various sleeves for use on beverage containers, none of these are particularly quantitative on the sleeve characteristics needed for good insulation.
It is also known to employ cup designs that emphasize insulation. Exemplary of such cup designs are U.S. Pat. No. 4,007,670 ('670) to J. V. Albano et al., entitled "Insulated Container," U.S. Pat. No. 4,261,501 ('501) to J. B. Watkins et al., entitled "Laminated Insulated Hot Drink Cup," U.S. Pat. No. 4,435,344 ('344) to A. Iioka, entitled "Method for Producing a Heat-Insulating Paper Container From a Paper Coated or Laminated With a Thermoplastic Synthetic Resin Film," U.S. Pat. No. 5,145,107 ('107) to V. K. Silver et al., entitled "Insulated Paper Cup," U.S. Pat. No. 5,226,585 ('585) to R. Varano, entitled "Disposable Biodegradable Insulated Container and Method for Making," U.S. Pat. No. 5,460,323 ('323) to J. H. Titus, entitled "Disposable Insulated Container," U.S. Pat. No. 5,542,599 ('599) to R. E. Sobol, entitled "Biodegradable Thermally Insulated Beverage Cup," U.S. Pat. No. 5,628,453 ('453) to D. M. MacLaughlin, entitled "Cup With Thermally Insulated Side Wall," U.S. Pat. No. 5,697,550 ('550) to R. Varano et al., entitled "Multi-Layered Insulated Cup Formed From Folded Sheet," U.S. Pat. No. 5,713,512 ('512) to R. K. Barrett, entitled "Polymeric Insulated Container," U.S. Pat. No. 5,752,653 ('653) to M. Razzaghi, entitled "Paper Cup With Air Insulation," U.S. Pat. No. 5,775,577 ('577) to J. H. Titus, entitled "Disposable Insulated Container With Microflute Structure," and U.S. Pat. No. 5,839,653 ('653) to R. B. Zadravetz, entitled "Container With Corrugated Wall." While a number of these references identify the effectiveness of an air gap and the providing of good insulation properties, they do not incorporate the simplicity of a sleeve cut from a single blank, add an air gap which is constructed of hot-melt glue dots, and employ a smooth outside-sleeve surface for printing.
It is apparent from the above that there exists a need in the art for a sleeve construction which is lightweight through simplicity of parts and uniqueness of structure, but which incorporates a sleeve cut from a single blank, adds an air-gap layer, and preserves a smooth outside-sleeve surface for printing. It is the purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.